Talc

Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H₂Mg₃( SiO₃)₄ or Mg₃Si₄O₁₀( OH)₂. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non- elastic although slightly flexible. It is sectile and very soft, with a hardness of 1 (Talc is the softest mineral on Mohs' scale). It has a specific gravity of 2.5 - 2.8, a waxlike or pearly luster, and is translucent to opaque. Its colour ranges from white to gray or green and it has a distinctly greasy feel.

Talc is a metamorphic mineral resulting from the alteration of silicates of magnesium such as pyroxenes, amphiboles, olivine and other similar minerals. It is usually found in metamorphic rocks, often of a basic type due to the alteration of the minerals mentioned above.

A coarse grayish-green talc has been called soapstone or steatite and has been used for stoves, sinks, electrical switchboards, etc. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a nappy (see diaper rash). Most tailor's chalk is talc, as is the chalk often used for welding or metalworking.

The origin of the name derives from the Persian via Arabic talq.

Talc is also used as food additive or in pharmaceutical products. In the European Community the additive number is E553b.

Safety

Several studies have established preliminary links between talc and pulmonary issues [1], ovarian cancer [2], and lung cancer [3] [4]. This is a major concern considering talc's widespread commercial and household use. However, no conclusive study has yet been made to determine either the toxicity and/or carcinogenic nature of talc and the long history of safe use suggests that these concerns are unfounded.

The U.S. Food and Drug Administration (FDA) considers non-asbestiform talc, that is talc which DOES NOT contain carcinogenic asbestos fibers, to be Generally Recognized As Safe (GRAS) for use in cosmetics.